The present invention relates to building materials, and more particularly, to a method of producing Keramzit used for making all types of light-weight concretes.
Known in the prior art is a method of producing Keramzit in rotary kilns which comprises treating clay to form a clayey mass, granulating it, drying the Keramzit granules formed at a temperature of 100.degree. to 150.degree. C., heat-treating the dried granules at 200.degree. to 500.degree. C., heating them from a temperature of 200.degree. to 500.degree. C. to a temperature of 1,100.degree. to 1,200.degree. C. for 15 to 20 minutes, calcining at 1,100.degree. to 1,200.degree. C. for 10 to 12 minutes and cooling to 50.degree. C. (S. P. Opatsky, Production of Keramzit).
Prolonged heating from a temperature of 200.degree.-500.degree. C. to a temperature of 1,100.degree.-1,200.degree. C. and restriction of the temperature conditions of calcining the granules to the upper limit of the temperature range of swelling (otherwise a sweating of the surface of Keramzit takes place) determine a higher bulk volume of Keramzit.
The above-mentioned method does not make it possible to produce Keramzit with a clinker-like compact crust having a varying thickness and ensuring its higher strength and lower water absorption.
This method does not make provision for accurate control of the temperature and the time of calcining crude Keramzit granules and thereby restricts the range of the Keramzit produced as regards its bulk density and strength.
The prior art teaches a method of manufacturing light-weight Keramzit which uses the effluent treatment product and clay as starting materials. The granules made from this mass are calcined at a temperature of 1,000.degree. to 1,200.degree. C. according to conventional technology (cf. the above reference). This method also does not make it possible to produce Keramzit with improved properties for the above reasons.
There is also known a circulation method of producing Keramzit in a spouting bed.
This method comprises partial drying, comminution of clay, granulation of the clayey mass in tray granulators, drying of the Keramzit granules formed at a temperature of 200.degree. C., calcining with a thermal shock at a temperature of 1,100.degree. to 1,200.degree. C. for 45 seconds in a spouting bed and subsequent cooling. The Keramzit produced features a hard, strong and thin envelope and a bulk density of 500 kg/m.sup.3.
The disadvantage of the above-described method lies in that it does not provide for the production of Keramzit with a swelled-up nucleus and a compact strong clinker-like crust of a varying thickness.
The Keramzit produced according to this method from the same clay and in the same thermal unit has a limited range as regards both the bulk density and the strength.